Interpretation: Telling the story of Yosemite National Park

What is this all about?

One project involving LandTrendr focuses on national parks in the western United States. A key piece of the work is to engage national park service interpreters in using change detection information to tell the story of their park. This section is designed to introduce interpreters to LandTrendr. We feel that the LandTrendr products may allow interpreters to:

  1. See the Park in a new way
  2. Show the Park’s dynamic nature
  3. Use new interpretation tools and graphics

 

How does the mapping process start?

First, we examine Landsat satellite images from 1984 to present, building a stack of information for the same place over many years.  Here we show an example from Yosemite National Park.

 

How do we map the changes? Tell me more

Rather than inferring change on a landscape from the differences in two satellite images at a time, we examine a time-series of as many as 25 satellite images at once which enables identifying distinct deviations from a stable spectral trajectory.

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How do we map the changes? Tell me even more

After identifying the shape of the trajectories for each pixel we are able to create a map labeling the results.

 
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What did we find? New ways of visualizing the earth.

These satellite images create opportunities for seeing the earth in a wholly dynamic new way such as through a sequence of images where 25 years passes in a 10-second animation. This is a view of Yosemite Valley 1984-2009.

Click here to see movies from other places

 

What did we find? More new ways of visualizing the earth.

In addition to animations, the results of the analysis can be viewed in a virtual earth such as Google Earth, NASA WorldWind, or ESRI ArcGlobe.

 
 

What did we find? Stable areas

White areas were those that exhibited an overall stable spectral trajectory.

 
 

What did we find? More stable areas

Areas exhibiting a stable spectral trajectory include forests, shrublands, grasslands, bare ground, and water.

 

What did we find? Even more stable areas

Identifying the spectrally stable areas of the landscape enables a greater understanding of the dynamic nature of an area.  Stable areas tend to exist in intact forests and are important for many animals.

 
 

What did we find? Vegetation growth

Identifying areas of vegetation growth.

 
   

What did we find? More Vegetation growth

Identifying areas of substantial vegetation growth and areas which did not regrow vegetation after a disturbance event highlights areas of particular interest. Areas in green are those that showed signs of growth.

 

What did we find? Even more vegetation growth

 

 

What did we find? Large and moderate disturbances.

Events such as fires, floods, avalanches were identified.

 
 

What did we find? More large and moderate disturbances.

It is well known that there are landscape altering disturbances such as forest fires. With our tools we can show what an area looked like before these big events and how the landscape changes after these events.

 

What did we find? Low level disturbances

Using a 25-year stack of satellite images provides the unique opportunity to identify low magnitude and multi-year disturbance events usually associated with insect outbreaks, forest mortality from drought or disease, and other slow processes.

 

What did we find? More low level disturbances

Using a 25-year stack of satellite images provides the unique opportunity to identify low magnitude and multi-year disturbance events usually associated with insect outbreaks, forest mortality from drought or disease, and other slow processes.

 

How can you use this in Interpretation?

How can this be used in Interpretation - wildfire example

Vegetation renewal:  a mosaic due to wildfire

2002 Wolf Fire was lightning caused and effectively managed for the benefit of the resource. Management of this fire demonstrated the best of wildland fire practices, cooperative efforts, and interpretive techniques.

 Yosemite National Park fire personnel and Rangers also seized the opportunity with the Wolf Fire and the neighboring Lukens Fire to lead walks to the fires. Safety for the visitor's was the first priority. The purpose of the walks was to challenge visitor's perceptions about wildland fire and to demonstrate a dynamic forest process. These fires were both low-intensity fires and easily demonstrated how fire cleanses the forest of fuel loads that can lead to catastrophic fires and how fire benefits the forest ecosystem. Visitors were able to see that fire is not only the catastrophic fire that is showcased in the media. Visitor interest was high and the program was always full. (http://www.nps.gov/archive/yose/news/2002/fire1120.htm)